Synthesis and performance of palladium-based electrocatalysts in alkaline direct ethanol fuel cell

The present study reports the performance enhancement of alkaline direct ethanol fuel cell (ADEFC) by using non-functionalized (Vulcan) and functionalized (Vulcan-F) carbon supported Pd, PdSn, PdNi and PdNiSn anodic electrocatalysts produced by impregnation-reduction method. The electrocatalysts are studied by thermogravimetric analysis (TGA), X-ray diffraction (XRD), transmission electron microscopy (TEM), cyclic voltammetry (CV), and ADEFC stability tests. TGA measurements of Vulcan evidence the characteristic weight losses attributed to the presence of surface functional groups due to the acid treatment. XRD shows that a higher degree of alloying is reached between Pd and Sn, whereas the Ni in PdNi and PdNiSn exists mostly segregated in the oxide form. TEM analysis indicates an agglomeration of Pd and PdSn particles, whereas a more uniform particle distribution is observed for PdNi and PdNiSn samples. CV curves show that the onset potential is shifted towards negative values for binary and ternary samples supported on functionalized Vulcan (Vulcan-F) indicating that the ethanol oxidation is facilitated on the functionalized surface. ADEFC fuel cell tests reveal that the highest open circuit voltage and maximum power density are achieved for the PdNiSn supported on Vulcan-F in which the characterizations evidenced improved textural properties.